<template>
  <div class="pagination">
      <!-- {{startAndEndNum}} -->
     <button :disabled="pageNo==1" @click="$emit('currentPage',pageNo-1)">上一页</button>
    <button v-if="startAndEndNum.start>=2" @click="$emit('currentPage',1)">1</button>
    <button v-if="startAndEndNum.start>=3">···</button>
    <button v-for="page in  startAndEndNum.end" :key="page" v-show="page>=startAndEndNum.start" :class="{active:pageNo==page}" @click="$emit('currentPage',page)">{{page}}</button>
    <button v-if="startAndEndNum.end < totalPage - 1">···</button>
    <button v-if="startAndEndNum.end < totalPage" @click="$emit('currentPage',totalPage)">{{ totalPage }}</button>
    <button :disabled="pageNo==totalPage" @click="$emit('currentPage',pageNo+1)">下一页</button>
    <button style="margin-left: 30px">共 {{ total }} 条</button>
  </div>
</template>

<script>
  export default {
    name: "Pagination",
    props:['total','pageSize','pageNo','continues'],
    computed: {
        //总共页码数
        totalPage(){
            return  Math.ceil(this.total / this.pageSize)
        },
        //计算连续页码数
        startAndEndNum(){
            const {totalPage,pageNo,continues} = this
            let start = pageNo - parseInt(continues/2);
            let end = pageNo + parseInt(continues/2);
            //判断当pageNo = 1||2
            if(start<1){
                start =1;
                end = continues;
            }
            //判断当pageNo = 33||34
            if(end > totalPage){
                end = totalPage
                start = totalPage - continues + 1;
            }

            return { start ,end };
        }
    }
  }
</script>

<style lang="less" scoped>
  .pagination {
      text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
</style>
